640707408 has 240 divisors, whose sum is σ = 2066867712. Its totient is φ = 190512000.

The previous prime is 640707377. The next prime is 640707413. The reversal of 640707408 is 804707046.

It is a happy number.

640707408 is a `hidden beast` number, since 640 + 7 + 0 + 7 + 4 + 0 + 8 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3036423 + ... + 3036633.

Almost surely, 2^640707408 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640707408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1033433856).

640707408 is an abundant number, since it is smaller than the sum of its proper divisors (1426160304).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640707408 is a wasteful number, since it uses less digits than its factorization.

640707408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 316 (or 298 counting only the distinct ones).

The product of its (nonzero) digits is 37632, while the sum is 36.

The square root of 640707408 is about 25312.1987982080. The cubic root of 640707408 is about 862.0912725025.

The spelling of 640707408 in words is "six hundred forty million, seven hundred seven thousand, four hundred eight".